Methods and devices for allocating resources for communications with base stations

ABSTRACT

A device may include a receiver configured to receive messages about first transmission rates provided by cooperation devices configured for device-to-device (D2D) communications in a radio communication system supporting the D2D communications; a determiner configured to determine second transmission rates for the device to suggest to the cooperation devices based on the first transmission rates; and/or a transmitter configured to transmit messages about the second transmission rates to the cooperation devices. The determiner may be further configured to change the second transmission rates until the first transmission rates converge. The determiner may be further configured to determine a final transmission rate suggested to the cooperation devices based on the converged first transmission rates.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority from Korean Patent Application No.10-2013-0028821, filed on Mar. 18, 2013, in the Korean IntellectualProperty Office (KIPO), the entire contents of which are incorporatedherein by reference.

BACKGROUND

1. Field

Some example embodiments may relate to methods and/or devices forallocating resources for communication with base stations.

2. Description of Related Art

Technologies for increasing a transmission rate while transmitting datafrom a base station to a device have been studied. The base station andthe device may transmit and receive data by using cellularcommunication. Here, two devices included in a network may pair up toreceive split data from the base station. The base station may transmitthe split data to each of the two devices by using a multi-inputmulti-output (MIMO) technology. The two devices transmit and receive thesplit data via device-to-device (D2D) communications. By using D2Dcommunications, radio resources may be efficiently used between the basestation and the devices, and a high transmission rate may be guaranteed.

SUMMARY

Some example embodiments may provide methods and/or devices forallocating resources for communication with base stations.

In some example embodiments, a device may comprise a receiver configuredto receive messages about first transmission rates provided bycooperation devices configured for device-to-device (D2D) communicationsin a radio communication system supporting the D2D communications; adeterminer configured to determine second transmission rates for thedevice to suggest to the cooperation devices based on the firsttransmission rates; and/or a transmitter configured to transmit messagesabout the second transmission rates to the cooperation devices. Thedeterminer may be further configured to change the second transmissionrates until the first transmission rates converge. The determiner may befurther configured to determine a final transmission rate suggested tothe cooperation devices based on the converged first transmission rates.

In some example embodiments, the determiner may be further configured todetermine a highest transmission rate from among the first transmissionrates as the final transmission rate suggested to the cooperationdevices.

In some example embodiments, the determiner may be further configured todetermine the second transmission rates based on previously determinedsecond transmission rates. The transmitter is further configured totransmit the second transmission rates to the cooperation devices.

In some example embodiments, when the first transmission rates converge,the determiner may be further configured to determine a cooperationdevice configured to provide a highest transmission rate as acooperation pair for the D2D communications.

In some example embodiments, the transmitter may be further configuredto transmit information about the determined cooperation pair and thefinal transmission rate to a base station.

In some example embodiments, the receiver may be further configured toreceive from a base station a total transmission rate between the basestation and cooperation pairs. The total transmission rate may beprovided when the device forms the cooperation pairs with thecooperation devices.

In some example embodiments, the determiner may be further configured todetermine the second transmission rates within a range of the totaltransmission rate.

In some example embodiments, the receiver may be further configured toreceive the first transmission rates. The determiner may be furtherconfigured to determine the second transmission rates based on the firsttransmission rates and previously determined second transmission rates.

In some example embodiments, the determiner may be further configured todistribute the second transmission rates obtained by excluding the firsttransmission rates and the previously determined second transmissionrates from a total transmission rate between a base station andcooperation pairs, according to a ratio determined with the cooperationdevices.

In some example embodiments, a method of allocating resources forcommunication between a device and a base station in a communicationsystem supporting device-to-device (D2D) communications may comprisedetermining a cooperation device to form a cooperation pair with anothercooperation device from among cooperation devices configured for the D2Dcommunications by exchanging messages about transmission rates providedbetween the cooperation devices until values of the transmission ratesprovided between the cooperation devices converge; and/or allocating theresources to the cooperation pair based on values of the convergedtransmission rates.

In some example embodiments, the determining may comprise determining acooperation device that provides a highest transmission rate from amongthe cooperation devices as the cooperation pair.

In some example embodiments, the determining may comprise determiningtransmission rates suggested by the device to the cooperation devicesbased on transmission rates provided by the cooperation devices; and/orchanging the transmission rates suggested to the cooperation devicesuntil values of the transmission rates suggested to the cooperationdevices converge.

In some example embodiments, the allocating may comprise allocating theresources corresponding to the converged transmission rates to thedetermined cooperation pair.

In some example embodiments, the determining may comprise transmittingand receiving messages about transmission rates suggested by the deviceto the cooperation devices and transmission rates provided to thecooperation devices.

In some example embodiments, the messages about the transmission ratessuggested to the cooperation devices may be determined based on messagesabout transmission rates provided by the cooperation devices receivedfrom the cooperation devices.

In some example embodiments, a device may comprise a receiver configuredto receive messages about first transmission rates from cooperationdevices configured for device-to-device (D2D) communications in a radiocommunication system supporting the D2D communications; a determinerconfigured to determine second transmission rates based on the firsttransmission rates; and/or a transmitter configured to transmit messagesabout the second transmission rates to the cooperation devices. Thedeterminer may be further configured to change the second transmissionrates until the first transmission rates converge. The determiner may befurther configured to determine a final transmission rate based on theconverged first transmission rates.

In some example embodiments, the device may be configured to allocateresources based on the converged first transmission rates.

In some example embodiments, the device may be configured to allocateresources based on the final transmission rate.

In some example embodiments, the transmitter may be further configuredto transmit information about the final transmission rate to a basestation.

In some example embodiments, the determiner may be further configured todetermine, when the first transmission rates converge, a highesttransmission rate from among the converged first transmission rates asthe final transmission rate.

In some example embodiments, the transmitter may be further configuredto transmit information about the final transmission rate to the basestation.

In some example embodiments, the transmitter may be further configuredto transmit information about a determined cooperation pair to the basestation.

In some example embodiments, the determiner may be further configured todetermine, when the first transmission rates converge, a cooperationdevice configured to provide a highest transmission rate as acooperation pair for the D2D communications.

In some example embodiments, the transmitter may be further configuredto transmit information about the determined cooperation pair to a basestation.

In some example embodiments, the transmitter may be further configuredto transmit information about a final transmission rate to the basestation.

In some example embodiments, the transmitter may be further configuredto transmit information about the determined cooperation pair to a basestation. The transmitter may be further configured to transmitinformation about the final transmission rate to the base station.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages will become more apparentand more readily appreciated from the following detailed description ofexample embodiments, taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram for describing a radio communication system;

FIG. 2 is a diagram for describing D2D communications;

FIG. 3 is a diagram for describing a device according to some exampleembodiments of the present inventive concept;

FIG. 4 is a flowchart illustrating a method of allocating resources,according to some example embodiments of the present inventive concept;

FIG. 5 is a flowchart illustrating a method of allocating resources,according to some example embodiments of the present inventive concept;

FIG. 6 is a diagram for describing a method of allocating resources,according to some example embodiments of the present inventive concept;and

FIG. 7 is a diagram for describing a method of allocating resources,according to some example embodiments of the present inventive concept.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings. Embodiments, however, may be embodied in manydifferent forms and should not be construed as being limited to theembodiments set forth herein. Rather, these example embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope to those skilled in the art. In the drawings, thethicknesses of layers and regions may be exaggerated for clarity.

It will be understood that when an element is referred to as being “on,”“connected to,” “electrically connected to,” or “coupled to” to anothercomponent, it may be directly on, connected to, electrically connectedto, or coupled to the other component or intervening components may bepresent. In contrast, when a component is referred to as being “directlyon,” “directly connected to,” “directly electrically connected to,” or“directly coupled to” another component, there are no interveningcomponents present. As used herein, the term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers, and/or sections, these elements, components, regions,layers, and/or sections should not be limited by these terms. Theseterms are only used to distinguish one element, component, region,layer, and/or section from another element, component, region, layer,and/or section. For example, a first element, component, region, layer,and/or section could be termed a second element, component, region,layer, and/or section without departing from the teachings of exampleembodiments.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,”“upper,” and the like may be used herein for ease of description todescribe the relationship of one component and/or feature to anothercomponent and/or feature, or other component(s) and/or feature(s), asillustrated in the drawings. It will be understood that the spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an,” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes,” and/or “including,” when used inthis specification, specify the presence of stated features, integers,steps, operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Example embodiments may be described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized example embodiments (and intermediate structures). As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, example embodiments should not be construed as limitedto the particular shapes of regions illustrated herein but are toinclude deviations in shapes that result, for example, frommanufacturing. For example, an implanted region illustrated as arectangle will typically have rounded or curved features and/or agradient of implant concentration at its edges rather than a binarychange from implanted to non-implanted region. Likewise, a buried regionformed by implantation may result in some implantation in the regionbetween the buried region and the surface through which the implantationtakes place. Thus, the regions illustrated in the figures are schematicin nature, their shapes are not intended to illustrate the actual shapeof a region of a device, and their shapes are not intended to limit thescope of the example embodiments.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andshould not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

Reference will now be made to example embodiments, which are illustratedin the accompanying drawings, wherein like reference numerals may referto like components throughout.

FIG. 1 is a diagram for describing a radio communication system.Referring to FIG. 1, the radio communication system includes a basestation 100 and a plurality of first through fourth devices 210 through240. In the radio communication system of FIG. 1, data may betransferred not only between the base station 100 and the first throughfourth devices 210 through 240, but also between the first throughfourth devices 210 through 240.

The base station 100 is radio communication equipment supporting a radiocommunication service of the first through fourth devices 210 through240. The base station 100 supports a communication technology, such ascode division multiple access (CDMA), global system for mobilecommunications (GSM), wideband code division multiple access (WCDMA), orlong term evolution (LTE) technology. The base station 100 transmitsdata to the first through fourth devices 210 through 240 by using thecommunication technology, such as CDMA, GSM, WCDMA, or LTE.

The base station 100 supports MIMO technology. MIMO technologysimultaneously transmits split data by using a plurality of antennas.The base station 100 includes a plurality of antennas to transmit splitdata by using the antennas. The base station 100 transmits the splitdata to the first through fourth devices 210 through 240 by usingdifferent radio resources. For example, the base station 100 maysimultaneously transmit the split data in different frequency bands byusing the plurality of antennas. In FIG. 1, the base station 100includes first and second antennas 110 and 120, but the number ofantennas included in the base station 100 is not limited to two.

The first through fourth devices 210 through 240 include communicationterminals, such as smart phones, tablet personal computers (PCs), orlaptops. The first through fourth devices 210 through 240 include anyelectronic device capable of transmitting and receiving data to and fromthe base station 100 or an adjacent device wirelessly or via wires.

The first through fourth devices 210 through 240 not only transmit andreceive data to and from the base station 100, but also communicate withanother device in a network. The first through fourth devices 210through 240 transmit and receive data to and from the base station 100,and transmit the received data to the other device or receive data fromthe other device.

The base station 100 may transmit data to the first through fourthdevices 210 through 240 via different frequency bands. In FIG. 1, thebase station 100 includes the first and second antennas 110 and 120, butthe number of antennas included in the base station may be more thantwo. In FIG. 1, reference characters h_(ab) denotes radio communicationbetween the base station 100 and the first through fourth devices 210through 240. In h_(ab), ‘a’ is an index indicating a device and ‘b’ isan index indicating an antenna of the base station 100. For example, areference numeral h₂₁ denotes radio communication between the seconddevice 220 and the first antenna 110 of the base station 100. The basestation 100 communicating with the first through fourth devices 210through 240 by using the first antenna 110 is denoted by h₁₁, h₂₁, h₃₁,and h₄₁. Also, the base station 100 communicating with the first throughfourth devices 210 through 240 by using the second antenna 120 isdenoted by h₁₂, h₂₂, h₃₂, and h₄₂.

FIG. 2 is a diagram for describing D2D communications. Referring to FIG.2, the first and second devices 210 and 220 form a cooperation pair andthe third and fourth devices 230 and 240 form a cooperation pair.

The first device 210 forms the cooperation pair with the second device220 so as to receive data. When the first and second devices 210 and 220form the cooperation pair, the first and second devices 210 and 220receive split data from the base station 100. Then, the first and seconddevices 210 and 220 exchange parts of the received split data. In otherwords, a part of the split data is transmitted from the base station 100to the first device 210 and a remaining part of the split data istransmitted to the second device 220. Here, the first and second devices210 and 220 may receive the split data from the base station 100 byusing different frequencies.

The first and second devices 210 and 220 transmit and receive datathrough the D2D communications. The first and second devices 210 and 220may transmit and receive data by using wireless fidelity (WiFi),Bluetooth, or near field communication (NFC).

FIG. 3 is a diagram for describing a device 300 according to someexample embodiments of the present inventive concept. Referring to FIG.3, the device 300 includes a receiver 310, a determiner 320, and atransmitter 330.

The receiver 310 receives data from the base station 100 or cooperationdevices 410 and 420. The receiver 310 receives split data from the basestation, and receives remaining data from any one of the cooperationdevices 410 and 420.

The receiver 310 receives a message about a total transmission rate fromthe base station 100. The total transmission rate indicates transmissionefficiency or a transmission rate provided from the base station 100when the device 300 forms a cooperation pair with any one of thecooperation devices 410 and 420. In other words, the total transmissionrate indicates a transmission rate allocable to two devices forming acooperation pair when the device 300 forms a cooperation pair with anyone of the cooperation devices 410 and 420. The transmission rateindicates allocable resources. For example, when resources allocable toa cooperation pair are increased, the total transmission rate isincreased. The allocable resources may indicate an allocable frequencyband. The receiver 310 outputs the received message about the totaltransmission rate to the determiner 320.

The receiver 310 receives messages about transmission rates providableby the cooperation devices 410 and 420 capable of D2D communications ina radio communication system supporting D2D communications. Thecooperation devices 410 and 420 denote devices capable of D2Dcommunications with the device 300. For example, the cooperation devices410 and 420 may be radio devices capable of communicating with thedevice 300 by being disposed adjacent to the device 300. The device 300receives messages about transmission rates providable by the cooperationdevices 410 and 420 from each of the cooperation devices 410 and 420. Inother words, the cooperation devices 410 and 420 calculate transmissionrates providable to the device 300 from among the total transmissionrate, and transmit messages about the calculated transmission rates tothe device 300.

The receiver 310 may be a device component for transmitting or receivingelectromagnetic waves in radio communication, such as an antenna.

The receiver 310 receives split data from a device forming a cooperationpair with the device 300. When the cooperation pair is determined, twodevices forming the cooperation pair receive split data from the basestation 100 by using MIMO technology. The receiver 310 receives a partof the split data from the base station 100, and receives a remainingpart of the split data from the device forming the cooperation pair.

The determiner 320 determines transmission rates that it suggests to thecooperation devices 410 and 420 based on the transmission ratesprovidable by the cooperation devices 410 and 420. The determiner 320receives the transmission rates providable by the cooperation devices410 and 420 from the receiver 310.

The determiner 320 changes the transmission rates suggested andprovidable to the cooperation devices 410 and 420 until the transmissionrates providable by the cooperation devices 410 and 420 converge, anddetermines a final transmission rate based on the converged transmissionrates (transmission rates suggested or providable to the cooperationdevices 410 and 420). The converging of the transmission rates meansthat transmission rates received by the device 300 from the cooperationdevices 410 and 420 are the same as transmission rates that the device300 previously received from the cooperation devices 410 and 420.Alternatively, the converging means that transmission rates transmittedfrom the device 300 to the cooperation devices 410 and 420 are constant.In other words, once messages about transmission rates are exchangedbetween the device 300 and the cooperation devices 410 and 420, valuesof the transmission rates included in the messages no longer change.When the values of the transmission rates no longer change, thedeterminer 320 determines that the transmission rates have converged,and determines the final transmission rate. The final transmission ratedenotes a transmission rate guaranteed in the device 300 when the device300 communicates via MIMO technology with any one of the cooperationdevices 410 and 420. In other words, the device 300 determines one ofthe cooperation devices 410 and 420 as a cooperation pair, i.e., thedevice 300 pairs with one of the cooperation devices 410 and 420. Thefinal transmission rate denotes a transmission rate when the device 300receives data from the base station 100 while communicating via MIMOtechnology with the determined cooperation device.

The determiner 320 determines a highest transmission rate from among thetransmission rates providable by the cooperation devices 410 and 420 asthe final transmission rate suggested to the cooperation devices 410 and420. When the transmission rates providable by the cooperation devices410 and 420 converge, the determiner 320 determines the highesttransmission rate from among the transmission rates providable by thecooperation devices 410 and 420. Then, the determiner 320 determines thehighest transmission rate as the final transmission rate.

The determiner 320 determines a cooperation device capable of providingthe highest transmission rate as a cooperation pair, i.e., as acooperation device for the device 300 to form a cooperation pair with.When the transmission rates providable by the cooperation devices 410and 420 are converged, the determiner 320 determines the cooperationdevice capable of providing the highest transmission rate from among thecooperation devices 410 and 420. The determiner 320 forms thecooperation pair with the determined cooperation device. After thecooperation pair is formed, devices forming the cooperation pairdetermine transmission rates for transmitting and receiving data to andfrom the base station 100 based on the converged transmission rates. Inother words, the devices forming the cooperation pair receive split databased on the transmission rates determined to the devices whilereceiving the split data from the base station 100. The devices formingthe cooperation pair operate as one virtual device having twotransmitters. Accordingly, the devices forming the cooperation pair maycommunicate via MIMO technology with the base station 100, as onevirtual device.

The transmitter 330 receives the final transmission rate from thedeterminer 320 to transmit the final transmission rate to the basestation 100. The final transmission rate denotes a transmission ratebetween the base station 100 and each device.

The transmitter 330 receives information from the determiner 320 aboutwhich cooperation device formed the cooperation pair with the device300, and transmits the information to the base station 100. In otherwords, the transmitter 330 transmits information to the base station 100about which one of the cooperation devices 410 and 420 is to form acooperation pair with the device 300.

The transmitter 330 transmits the split data to the device forming thecooperation pair. The device 300 receives the split data from the basestation 100, and the transmitter 330 transmits the received split datato the device forming the cooperation pair.

The base station 100 transmits the split data to each of devices forminga cooperation pair. The base station 100 receives information from thedevice 300 about which devices have formed a cooperation pair and aboutdetermined transmission rates of the devices forming the cooperationpair. The base station 100 allocates radio resources to the devicesforming the cooperation pair based on the determined transmission rates.The base station 100 uses the allocated radio resources to transmitsplit data to the devices. In other words, the base station 100 splitsone piece of data into two pieces of split data, and transmits the twopieces of split data respectively to the devices.

FIG. 4 is a flowchart illustrating a method of allocating resources,according to some example embodiments of the present inventive concept.FIG. 4 is a flowchart for describing allocating of resources asperformed by the device 300 of FIG. 3. Accordingly, details about thedevice 300 described above are also applied to the method of FIG. 4,even if omitted.

In operation 510, the device 300 exchanges messages about transmissionrates providable to and from cooperation devices capable of D2Dcommunications until the transmission rates converge so as to determinea cooperation device with which to form a cooperation pair from amongthe cooperation devices. The device 300 determines the cooperationdevice to form the cooperation pair with based on the convergedtransmission rates.

For example, the cooperation devices capable of D2D communications aredevices disposed adjacent to the device 300 and capable of transmittingand receiving data to and from the device 300 via communication, such asWiFi. The device 300 transmits messages about transmission ratesprovidable by the device 300 to the cooperation devices, and thecooperation devices transmit messages about transmission ratesprovidable by the cooperation devices to the device 300. In other words,the device 300 and the cooperation devices exchange messages aboutprovidable transmission rates.

The device 300 and the cooperation devices exchange the messages aboutthe providable transmission rates until values of the providabletransmission rates no longer change. In other words, the device 300 andthe cooperation devices exchange the messages until recent values ofprovidable transmission rates are equal to values of the next providabletransmission rates to be transmitted.

In operation 520, the device 300 allocates resources to the cooperationpair based on the converged transmission rates. The device 300determines a cooperation device having a highest providable transmissionrate as the cooperation device with which to form the cooperation pair.The device 300 allocates resources to the cooperation device forming thecooperation pair with the device 300, based on the transmission rateprovidable to the cooperation device forming the cooperation pair withthe device 300.

FIG. 5 is a flowchart illustrating a method of allocating resources,according to some example embodiments of the present inventive concept.FIG. 5 is a flowchart for describing allocating of resources performedby the device 300 of FIG. 3. Accordingly, details about the device 300described above are also applied to the method of FIG. 5, even ifomitted.

In operation 610, the device 300 exchanges messages about transmissionrates providable to each other with cooperation devices capable of D2Dcommunications.

In operation 620, the device 300 determines whether values of thetransmission rates have converged. If the values have converged,operation 640 is performed, and if not, operation 630 is performed.

In operation 630, the device 300 changes the transmission ratesprovidable to the cooperation devices. The changed transmission ratesare again transmitted to the cooperation devices via exchanged messagesin operation 610.

In operation 640, the device 300 determines a cooperation device capableof providing a highest transmission rate from among the cooperationdevices as a cooperation device with which to form a cooperation pair.In other words, the device 300 receives a plurality of messages aboutthe transmission rates from the cooperation devices. Then, the device300 determines a message about a highest transmission rate from amongthe plurality of messages. The device 300 determines a cooperationdevice that transmitted the determined message as a cooperation pair.

In operation 650, the device 300 allocates resources based on a finaltransmission rate exchanged with the cooperation device determined to bethe cooperation pair. Radio resources used to transmit data from thebase station 100 to the device 300 and the cooperation device determinedto be the cooperation pair are allocated based on the final transmissionrate. In other words, the radio resources between the base station 100and the device 300 are determined according to a transmission rateprovidable from the cooperation device determined to be the cooperationpair to the device 300. In other words, radio resources for guaranteeinga determined transmission rate are allocated to the device 300. Radioresources for guaranteeing a transmission rate providable by the device300 are also allocated to the cooperation device determined to be thecooperation pair.

Total radio resources allocated to the device 300 and the cooperationdevice determined to be the cooperation pair are received from the basestation 100. In other words, the device 300 pre-receives a totaltransmission rate between the base station 100 and the cooperation pair,which is provided when the device 300 forms the cooperation pair withthe cooperation device. The total transmission rate differs based onwhich cooperation device forms the cooperation pair with the device 300.

FIG. 6 is a diagram for describing a method of allocating resources,according to some example embodiments of the present inventive concept.In FIG. 6, the base station 100 includes the first through fourthdevices 210 through 240. Also in FIG. 6, the first through fourthdevices 210 through 240 are indicated as circles that are connected toeach other by lines.

Devices connected in a line denote that they are capable of D2Dcommunications. For example, the first device 210 is capable of D2Dcommunications with the second device 220, and the second device 220 iscapable of D2D communications with the first and third devices 210 and230.

Referring to signs in FIG. 6, ‘ ’ and ‘j’ are indexes for classifyingdevices. w_(ij) denotes a total transmission rate guaranteed when thebase station communicates with devices forming a cooperation pair, whena device_(i) and a device_(j) form a cooperation pair. m_(j→i) denotes amessage about a transmission rate providable from the device_(j) to thedevice_(i). α^(t) _(i/j) denotes a message about a transmission ratesuggested from the device_(i) to the device_(j). Here, t denotes anumber of times a message is transmitted or a time taken to transmit amessage. For example, w₁₂ denotes a total transmission rate guaranteedwhen the first and second devices 210 and 220 forming a cooperation paircommunicate with the base station 100. m_(2→1) denotes a message about atransmission rate providable by the second device 220 to the firstdevice 210. a² _(3/1) denotes a message about a second transmission ratesuggested by the third device 230 to the first device 210.

For convenience of description, in FIGS. 6 and 7, transmission rates areindicated by only indicating numbers on lines. w_(ij) is indicated abovea center of a line. m_(j→i) is indicated above a left side of the line,and m_(j→i) is indicated above a right side of the line. a^(t) _(i/j) isindicated below the left side of the line, and a^(t) _(j/i) is indicatedbelow the right side of the line.

Messages about transmission rates transferred between the first throughfourth devices 210 through 240 will now be described with reference toFIG. 6. In FIG. 6, the first device 210 is capable of D2D communicationswith the second device 220. Accordingly, D2D communications is notpossible if the first device 210 does not form a cooperation pair withthe second device 220. The second device 220 is capable of D2Dcommunications with the first and third devices 210 and 230.Accordingly, the second device 220 exchanges messages about transmissionrates with the first and third devices 210 and 230 so as to form acooperation pair with a device providing a higher transmission rate fromamong the first and third devices 210 and 230. The third device 230 iscapable of D2D communications with the second and fourth devices 220 and240. The fourth device 240 is capable of D2D communications with thethird device 230.

Numbers shown in FIGS. 6 and 7 show sizes of transmission rates, whereinunits of transmission rates may be in any form, such as bits per second(bps), kilobits per second (kbps), or Hertz (Hz) or cycles per second.In FIGS. 6 and 7, only numbers are shown for convenience of description.

FIG. 7 is a diagram for describing a method of allocating resources,according to some example embodiments of the present inventive concept.Referring to FIG. 7, dealings of transmission rates between the firstthrough fourth devices 210 through 240 are illustrated. In other words,the first through fourth devices 210 through 240 make a deal todetermine which transmission rates they will provide to one another,through bidding of transmission rates. In FIG. 7, transmission rates areconverged through 9 operations from t=0 to final.

The first through fourth devices 210 through 240 each calculatetransmission rates providable to corresponding cooperation devices andsuggested to the corresponding cooperation devices. A cooperation devicedenotes a device capable of D2D communications with a correspondingdevice. For example, a cooperation device of the first device 210 is thesecond device 220, and cooperation devices of the second device 220 arethe first and third devices 210 and 230.

An example of a method of a device calculating transmission ratesprovidable to cooperation devices will now be described. The firstthrough fourth devices 210 through 240 calculate transmission ratesprovidable to cooperation devices by using Equation 1 below.

$\begin{matrix}{m_{i\rightarrow j}^{t} = {\left( {w_{ij} - a_{i/j}^{t}} \right)_{+} - {\frac{1}{2}\left( {w_{ij} - a_{i/j}^{t} - a_{j/i}^{t}} \right)_{+}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, + next to a set of brackets denotes a positive value whena value inside that set of brackets is positive, and a function having 0when the value inside that set of brackets is lower than 0. Equation 1is used to calculate a transmission rate providable by the device_(i) tothe device_(j). When the device_(i) forms a cooperation pair with thedevice_(j), a transmission rate (m_(i→j) ^(t)) suggested to thedevice_(j) is calculated based on a total transmission rate (w_(ij)), atransmission rate (a^(t) _(i/j)) suggested by the device_(i) to thedevice_(j), and the transmission rate (a^(t) _(j/i)) suggested by thedevice_(j) to the device_(i).

An example of a method of a device calculating transmission ratessuggested to cooperation devices will now be described. The firstthrough fourth devices 210 through 240 calculate transmission ratessuggested to cooperation devices by using Equation 2 below.

a _(i→j) ^(t+1) =s·max_(kεN(i)ij)(m _(k→i) ^(t)) or (1−s)a _(i→j) ^(t)+s·max_(kεN(i)ij)(m _(k→i) ^(t))  [Equation 2]

In Equation 2, max denotes a function for selecting a highest value fromamong values of m^(t) _(k→i). ‘t+1’ may denote an operation higher thant by 1, or that it is calculated temporally after t. N(i)/j denotesremaining cooperation devices obtained after excluding the device_(j)from among cooperation devices of the device_(i). In other words, N(i)/jdenotes cooperation devices excluding the device while the device_(i)calculates a^(t+1) _(i→j) to be transmitted to the device_(j). Forexample, when the second device 220 calculates a^(t+1) _(2→3), N(2)/3 isthe first device 210. ‘s’ is a value for adjusting a scale, as desiredby a user (and may or may not be predetermined).

The device_(i) selects a value of a highest transmission rate inmessages (m^(t) _(k→i)) transmitted from cooperation devices to thedevice_(i), and calculates transmission rates (a^(t+1) _(i→j)) suggestedby the device_(i) to the cooperation devices.

When exchanged transmission rates converge, the device 300 determines afinal transmission rate according to Equation 3 below.

r _(i)=max_(kεN(i))(m ^(t) _(k→i))  [Equation 3]

The device 300 determines a highest transmission rate, from amongprovidable transmission rates received from cooperation devices, as afinal transmission rate. r_(i) denotes a final transmission ratedetermined by the device_(i).

Dealing of transmission rates as four devices exchange messages will nowbe described with reference to FIG. 7.

A total transmission rate when devices form a cooperation pair will nowbe described. A total transmission rate of the first and second devices210 and 220 is 8, and a total transmission rate of the second and thirddevices 220 and 230 is 6. A total transmission rate of the third andfourth devices 230 and 240 is 2.

At t=0, the first through fourth devices 210 through 240 exchangemessages about transmission rates providable to each other and messagesabout transmission rates suggested to each other. For example, atransmission rate providable to the first device 210 by the seconddevice 220 is 4, and a transmission rate providable to the third device230 by the second device 220 is 3. A transmission rate providable to thesecond device 220 by the first device 210 is 4, and a transmission rateprovidable to the second device 220 by the third device 230 is 3. Att=0, transmission rates suggested by the first through fourth devices210 through 240 are 0.

At t=1, the first through fourth devices 210 through 240 exchangemessages about transmission rates providable to each other and suggestedto each other based on the messages exchanged at t=0. Based on thesecond device 220, the second device 220 calculates m¹_(2→1)(=(8−3)₊−0.5*(8−3−0)=2.5) providable to the first device 210according to Equation 1. Also, the second device 220 calculates m¹_(2→3)(=(6-4)₊−0.5*(6−4−1)=1.5) providable to the third device 230according to Equation 1.

Also, since the second device 220 suggests one of received m⁰ _(1→2) andm⁰ _(3→2) to the first device 210 while calculating a¹ _(2→1) suggestedto the first device 210 according to Equation 2, the second device 220suggests m⁰ _(3→2) excluding m⁰ _(1→2) received from the first device210, to the first device 210. In this case, since only m⁰ _(3→2)received from the third device 230 is left when m⁰ _(1→2) received fromthe first device 210 is excluded, the second device 220 suggests m⁰_(3→2) to be a¹ _(2→1) to the first device 210. If m⁰ _(3→2), m⁰ _(4→2),etc. are received from a plurality of devices excluding m⁰ _(1→2)received from the first device 210, the second device 220 selects ahighest value from among m⁰ _(3→2), m⁰ _(4→2), etc. to be suggested tothe first device 210. Here, s=1.

At t=2 through t=7 and final, the first through fourth devices 210through 240 exchange messages about transmission rates based onEquations 1 and 2 as described above. Here, at t=7 and final, values oftransmission rates that are exchanged are not changed. In this case, thefirst through fourth devices 210 through 240 determine that transmissionrates have converged, and determine final transmission rates andcooperation pairs. In FIG. 7, the first and second devices 210 and 220form a cooperation pair and the third and fourth devices 230 and 240form a cooperation pair.

For example, in the second device 220, since the first device 210 iscapable of providing a transmission rate of 6.5 and the third device 230is capable of providing a transmission rate of 5, the first device 210is determined as a cooperation pair. Also, the first and second devices210 and 220 allocate resources based on transmission rates of 1.5 and6.5, which are final transmission rates. Information about the allocatedresources is transmitted to the base station 100.

If two devices form a cooperation pair, a relationship ofr_(i)+r_(j)=w_(ij) is established, and if not, a relationship ofr_(i)+r_(j)≧w_(ij) is established. If two devices form a cooperationpair and surplus transmission rates remaining after achieving alltransmission rates of data individually expected by the two devices arethe same, a condition of Equation 4 below is achieved.

r _(i)−max_(kεN(i)/j)(w _(ik) −r _(k))₊ =r _(j)−max_(lεN(j)/i)(w _(jl)−r _(l))₊  [Equation 4]

If the surplus transmission rates are not the same, a relationship ofEquation 5 is achieved according to p_(ij) and p_(ji) indicating ratiosthereof.

$\begin{matrix}{{\frac{1}{p_{ij}}\left\{ {r_{i} - {\max_{k \in {{N{(i)}}/j}}\left( {w_{ik} - r_{k}} \right)_{+}}} \right\}} = {\frac{1}{p_{ij}}\left\{ {r_{j} - {\max_{l \in {{N{(j)}}/i}}\left( {w_{jl} - r_{l}} \right)_{+}}} \right\}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$

Also, if the surplus transmission rates are not the same, the device 300calculates a transmission rate providable to a cooperation deviceaccording to Equation 6 below.

m _(i→j) ^(t)=(w _(ij) −a _(i/j) ^(t))₊ −p _(ij)(w _(ij) −a _(i/j) ^(t)−a _(j/i) ^(t))₊  [Equation 6]

Devices in a network determine a cooperation pair for D2D communicationsby using the above method. Also, devices forming a cooperation paircommunicate via MIMO technology with a base station according todetermined final transmission rates, and thus individual devices mayallocate resources regardless of a base station. In addition, atransmission rate throughout a network may be increased by using amethod according to some example embodiments of the present inventiveconcept compared to a method of determining a transmission rate afterdetermining a cooperation pair for transferring resources between alldevices in a network.

As described above, according to some example embodiments of the presentinventive concept, a cooperation pair of devices for obtaining mostefficient transmission rates in a network can be determined.

By determining the cooperation pair based on messages transferredbetween the devices, the cooperation pair can be determined regardlessof a base station.

Some example embodiments of the present inventive concept can be writtenas computer programs and can be implemented in general-use digitalcomputers that execute the programs using a computer readable recordingmedium. Examples of the computer readable recording medium includemagnetic storage media (e.g., read-only memory (ROM), floppy disks, harddisks, etc.), optical recording media (e.g., compact disc read-onlymemories (CD-ROMs), or digital video discs (DVDs)), etc.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

What is claimed is:
 1. A device, comprising: a receiver configured to receive messages about first transmission rates provided by cooperation devices configured for device-to-device (D2D) communications in a radio communication system supporting the D2D communications; a determiner configured to determine second transmission rates for the device to suggest to the cooperation devices based on the first transmission rates; and a transmitter configured to transmit messages about the second transmission rates to the cooperation devices; wherein the determiner is further configured to change the second transmission rates until the first transmission rates converge, and wherein the determiner is further configured to determine a final transmission rate suggested to the cooperation devices based on the converged first transmission rates.
 2. The device of claim 1, wherein the determiner is further configured to determine a highest transmission rate from among the first transmission rates as the final transmission rate suggested to the cooperation devices.
 3. The device of claim 1, wherein the determiner is further configured to determine the second transmission rates based on previously determined second transmission rates, and wherein the transmitter is further configured to transmit the second transmission rates to the cooperation devices.
 4. The device of claim 1, wherein when the first transmission rates converge, the determiner is further configured to determine a cooperation device configured to provide a highest transmission rate as a cooperation pair for the D2D communications.
 5. The device of claim 4, wherein the transmitter is further configured to transmit information about the determined cooperation pair and the final transmission rate to a base station.
 6. The device of claim 1, wherein the receiver is further configured to receive from a base station a total transmission rate between the base station and cooperation pairs, and wherein the total transmission rate is provided when the device forms the cooperation pairs with the cooperation devices.
 7. The device of claim 6, wherein the determiner is further configured to determine the second transmission rates within a range of the total transmission rate.
 8. The device of claim 1, wherein the receiver is further configured to receive the first transmission rates, and wherein the determiner is further configured to determine the second transmission rates based on the first transmission rates and previously determined second transmission rates.
 9. The device of claim 1, wherein the determiner is further configured to distribute the second transmission rates obtained by excluding the first transmission rates and the previously determined second transmission rates from a total transmission rate between a base station and cooperation pairs, according to a ratio determined with the cooperation devices.
 10. A method of allocating resources for communication between a device and a base station in a communication system supporting device-to-device (D2D) communications, the method comprising: determining a cooperation device to form a cooperation pair with another cooperation device from among cooperation devices configured for the D2D communications by exchanging messages about transmission rates provided between the cooperation devices until values of the transmission rates provided between the cooperation devices converge; and allocating the resources to the cooperation pair based on values of the converged transmission rates.
 11. The method of claim 10, wherein the determining comprises determining a cooperation device that provides a highest transmission rate from among the cooperation devices as the cooperation pair.
 12. The method of claim 10, wherein the determining comprises: determining transmission rates suggested by the device to the cooperation devices based on transmission rates provided by the cooperation devices; and changing the transmission rates suggested to the cooperation devices until values of the transmission rates suggested to the cooperation devices converge.
 13. The method of claim 10, wherein the allocating comprises allocating the resources corresponding to the converged transmission rates to the determined cooperation pair.
 14. The method of claim 10, wherein the determining comprises transmitting and receiving messages about transmission rates suggested by the device to the cooperation devices and transmission rates provided to the cooperation devices.
 15. The method of claim 14, wherein the messages about the transmission rates suggested to the cooperation devices are determined based on messages about transmission rates provided by the cooperation devices received from the cooperation devices. 